A typical ventilated range with plug-in units permitting insertion, alternately, of any one of several various plug-in cooking devices is disclosed in Cerola U.S. Pat. No. 3,797,375. Approval of such ranges by safety inspecting bodies, such as United Laboratories, requires that the surface unit ventilating fan be automatically placed in operation whenever the plug-in broiling or grill element is energized. In these ranges, flexibility of operation requires that the receptacle in the range accomodate either a plug-in broil element (requiring ventilating fan operation) or, alternatively, a two element surface cooking plug-in cartridge (not requiring ventilating fan operation). The surface cooking cartridge incorporates conventionally spaced front and rear heating elements and these are individually controlled, as is conventional by separate, range mounted, manually operated control switches. That switch controlling a certain one of the cartridge heating units, conventionally the rear one, must also double as the controlling switch for the broil element when it is inserted in the range in place of the surface cooking cartridge. Wiring the switch, the broil element and the ventilating fan drive motor in series-parallel relation results in unnecessary (and sometimes undesirable) operation of the ventilating fan whenever the rear heating element of the surface cooking cartridge is energized. The rear heating element cannot be operated without operation of the ventilating fan although safety requirements indicate only that the broil element, when it replaces the surface cooking cartridge, must be operated with the ventilating fan.
The prong and socket circuit arrangement necessary to eliminate this difficulty is disclosed herein and forms the subject matter of the present invention.